This project aims at an understanding of the structure and dynamics of chromatin. In particular, we are concerned about the involvement of tubulin, histones, and other chromosomal proteins in the condensation of chromatin, and in separation of sister chromatids during the various phases of the cell cycle and in cell division. The primary structures of H1 histones are being determined, and their interactions with various physical forms of DNA and chromatin fragments are being observed by circular dichroism, etc. The synthesis of histones H1 and H1 degree will be related to the cell cycle and cell division. Factors affecting the assembly of microtubules from tubulin are to be studied by searching for presently unknown accessory proteins or other components that vary from one cell type to another or from one physiological state to another. In addition, the role of factors (e.g., trinucleotides) common to all microtubular systems will be investigated.